In regards to the anon asking about the acromantulas: they didn't seem to be on anyone's side. I just finished reading DH2 and they were pretty much just going where they wanted and doing what they wanted. I know the Death Eaters ran them out of their area (becuase that's where the scene with Voldemort and Harry took place in the books). I think the acromantulas were rather neutral and just really wanted fresh meat.